Well guys I think most everybody likes 1/2 turn preload on hydraulic lifters. When I post the question about how much preload I should adjust to, the most common answer is 1/2 turn. Everybody says a full turn would hold the valve off the seat. If this were true, how can the manufacturer recommend 1 full turn? I guess my biggest thing is: right now my valves clatter at 1/2 turn, and I'm thinking of trying a full turn. Is anybody running a full turn preload with, or without problems. Remember this is a stock engine. Maybe it's different for aftermarket lifters. I'm not flaming or saying anybody is wrong, I would just like to know the reasons behind the recommendations. I beleive the book also said that a full turn would be putting the lifter halfway thru it's travel. What gives??????

I wouldn't worry too much about how much you turn the nut down. Just turn it enough so the valves are quiet but not so much as to make the engine start to miss. Not all valves are going to adjust the exact same amount. With a little practice you will be able to do this in your sleep.

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Bob (Creedmoor,N.C.)
65 Vette B&M Blown, Richmond 5-speed
68 Malibu B&M Blown, Turbo 350 10" converter

Just for the heck of it I adjusted a lifter down over 2 1/2 turns once before it bottomed out. Mostly a matter of preference these days as lifters generally won't "pump up" and float the valves. Sometimes you can readjust and by changing the position of the plunger, it will quiet them down a little, seems like. Sometimes, nothing helps.

Thanks guys. I thought myself I had this valve thing licked. Hell even my girlfriend knows how to adjust the damn valves. I always use to adjust them down a full turn, but then everybody was saying no, no. I just wanted to hear from somebody else who thinks a full turn isn't going to to far. Thanks again Ronnie

If they don't clatter, I go 1/2 turn. If just one clatters any at all, I go 3/4 turn. I never go 1 turn.

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Tom Parsons

Are you adjusting the valves while the engine is running. If you adjust (while engine running) out the pinging of the lifter than go 1/4 to 1/2 turn you should be fine. Let us know how you are adjusting the lifters.

Thanks

With the engine off, but hot. One cylinder at a time, every 90 degrees per the damper. The damper is correct, it's been verified by a degree wheel

My valves only clatter on startup, after about three seconds it goes away. But even with my engine off for five minutes, they'll clatter again on startup

If you call a lifter manufacturer they will tell you that a lifter is suppose to have a certain amount of preload measured in thousandths of an inch. To get this preload you need to measure with a dial indicator for the suggested movement, or figure out how many turns that equates to on the adjusting nut; given the thread pitch of the stud. So, it varies depending on the thread pitch and manufacturers recommended preload.

The factory adjustment is 1 turn. Lifter manufacturers want about .050" preload...on a 3/8 X 24 thread rocker stud, 1 turn is .042"
The reason most cam manufacturers, and engine builders only go 1/4 turn or so is to prevent problems if the motor is run at an rpm that allows valve float. A hydraulic lifter is designed to keep the valve train at "zero" lash. It adjusts itself as it runs to take all the lash out of the system. If a valve floats, it stays open as the lifter starts down the back side of the cam...the lifter sees extra lash, and pumps up to eliminate it. On the next cycle, the lifter is still pumped up and, if the clearances are real close, the valve smacks the piston.
Comp Cams actually has a hydraulic lifter that you run at zero lash. It is basically running up against the lock ring all the time. This is for high rpm motors that must use a hydraulic cam due to race rules.
In a normal street application, it probably does not matter what the preload is as long as there is some. The newer Big Blocks have a non adjustable valve train. The preload is set at the factory. You can mill the heads on those motors quite a bit, and still not have any problems.
So unless you are building a 8000 rpm race motor, it is really not all that critical.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

Everyone thinks you loose lift setting at 1 turn (not true).If you think 1 is too much and 1/2 is not enough go 3/4.Like Bill said it is not that critical,and every stud I've seen on Chevys is fine thread...FRED

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